Hydrocarbon fluids such as oil and natural gas are obtained from a subterranean geologic formation (i.e., a "reservoir") by drilling a well that penetrates the hydrocarbon-bearing formation. Once a wellbore has been drilled, the well must be "completed" before hydrocarbons can be produced from the well. A completion involves the design, selection, and installation of tubulars, tools, and other equipment that are located in the wellbore for the purpose of conveying, pumping, or controlling the production or injection of fluids. After the well has been completed, production of oil and gas can begin.
Each of these phases (drilling, completion, and production) make use of a complex variety of equipment, including tubular members such as casing, production tubing, landing nipples, and gas lift mandrels; flow control devices such as gas lift valves, subsurface safety valves, and packers; and other equipment, such as perforation guns. In many situations it is necessary to lower one piece of equipment into the well so that it can be installed into a particular location in the wellbore (e.g., installing a gas lift valve in a particular gas lift mandrel when there may be several gas lift mandrels at different depths in the wellbore), or alternatively can perform a desired action at a desired location (e.g., a perforating gun that uses shaped charges to create holes in well casing at a particular depth in the well).
In the past, rather complex means have been used to determine when a given piece of downhole equipment is in the desired location in the wellbore. These methods have often been imprecise, complex, and expensive. For example, a wireline retrievable subsurface safety valve can be lowered into a wellbore on a wireline to be installed in a particular landing nipple. If multiple landing nipples are located in the wellbore, generally the uppermost one must have the largest inner diameter, and each succeeding lower nipple must have a smaller inner diameter, so that the valve may be placed at the desired depth in the well. This requires the use of multiple sizes (i.e., inner diameters) of landing nipples, as well as corresponding sizes of safety valves. Thus, while this technique for installing and/or activating downhole tools in a wellbore works, it can be complex and cumbersome in certain instances.
There is a long-standing need for more intelligent and adaptable methods of drilling and completing wells and of producing fluids therefrom.